At present, technical and economic advantages of the DC power transmission are accelerating the construction and development of the DC power network. The set of all branch-transferred power flows corresponding to an operation state of the DC power network is the base of its control. Thus a good power flow obtaining method, especially a reliable, fast, accurate and globally-linear one, is expected to be developed urgently.
The existing power flow obtaining method for DC power networks is firstly building a system of nonlinear bus power balance equations as the power flow model, then solving it using iterative method and calculating each branch-transferred power. Resulting from the nonlinearity of the power flow model, the existing method is computation-intensive, time-consuming and may be unreliable in convergence, thus difficult to satisfy the real-time requirement of DC power network control. If the linearized model at an operation base point is used to obtain power flows, the resultant locally linear characteristics will lead to being unable to satisfy the control accuracy requirement under wide range change of the operation point of the DC power network. As a result, the existing power flow obtaining method for DC power networks is either time-consuming and unreliable in convergence, or unable to satisfy the control accuracy requirement under wide range change of the operation point of the DC power network.